I'm having an issue where there's excessive fuel tank pressure building under hot conditions on the race track. Fuel sprayed out the gas cap. I borrowed a gas cap from another S2000 and did 2 laps instead of a whole session and there was a lot of pressure inside, but I guess it wasn't enough to blow the gas cap yet.

When there is high pressure in the tank and I remove the gas cap while the engine is running, the car sputters and dies. When there is not high pressure in the tank, the engine keeps running with the gas cap removed. Not sure what this means. Guessing something to do with vacuum and EVAP?

All of the EVAP solenoids I assume the ECU can tell if they are not working correctly and show a CEL, so my best guess is the two-way valve, which is mechanical. The car drives normally and there is no CEL. Has anybody else experienced anything like this?

 

Maybe an issue with fuel lines for EVAC system. Or bad valves within the system. See pages 358-375, of link.

Manual.

 

Everything stock including ecu?

 

Yes, everything is stock. The car has sat for a year with little use.

 

Clogged charcoal canister maybe?